Balance control?

https://imgur.com/gallery/SOuJ60E

Not sure how it operates electrically, but the manual says they can be used for channel to channel gain matching when replacing tubes 

The trim pots in the Herron might alter plate resistance on the input voltage amplifier tubes, which would affect gain. In my opinion most audiophiles would get in trouble fiddling with such a parameter. Or they may operate in some other way. Regardless, Atmasphere said all that needs to be said, to help the OP. I hope he is following the advice already given.

It’s pretty slick he has that inside there, the range of adjustment isn’t huge by any means, but it was enough to balance out the very slight imbalance I was getting. Took forever to track down what it was, did all the steps above, cart good, cables good, speakers/room placement symmetrical to the 1/16th of an inch. That simple little tweak of the pots brought it into perfect focus.

@bimmerman2 

Awesome Keith did that! That's a great mod. I wish more preamps with analog volume controls would provide a few high quality (high quality resistors) discrete steps of ~ 1/3rd dB in each direction L/R. That should provide enough flexibility for most use cases (more than 1 - 1.5 dB cumulative imbalance and something is wrong) without a significant SQ penalty. 

They are different from the loading plugs, which I don’t use with my Aphelion cartridge as per Keith’s suggestion. The pots are inside next to the tubes and are labeled, you just have to remove the top cover. You can turn them with a small screwdriver. On mine I ended up having to lower the louder channel a bit and increase the quieter one as the adjustment range isn’t huge. I’ll post a picture in my virtual systems section under "Final Set" so you can see them. They are the little blue pots. There are 3 per channel, gain, trim and bias. Don't mess with the bias pots. 

@bimmerman2 wow really?! That’s very cool. Yeah Keith is a very helpful and pleasant guy to chat with. What are trim pots? Are they different from the loading plugs?

Resurrection of an old thread, but I also run a Herron VTPH-2A phono stage. Keith was kind enough to include gain and trim pots for each channel to help with tube imbalance if this is indeed the case. There can be many causes, as per the posts above, but if you trace it back to the phono stage don't be afraid to try a little trim. 

@woofman74 fair enough. Thanks for the input to you and everyone here. Much appreciated! 

Lewm and Slaw are correct. Using the placement of a vocalist in the mix is not reliable.
And if your problem is not electronic you could be obsessing over something that could have you chasing your tail for some time, instead of enjoying your records.

Here’s something that happened to me.
After upgrading my turntable table in 2020 I pulled out a test record I had picked up at a used record fair for $1. My main purpose was to check the anti-skating. But a couple of tracks also helped me to evaluate channel balance, which up to that point I thought was just fine. Turns out, it wasn’t, It was skewed noticeably to one side.

Even though my speakers are are equidistant from the side walls and the wall behind them my room layout is asymmetrical. I have CD racks on one side and records on the other and the location of doors, windows, electric outlets together with media storage dictated placement of everything that goes against a wall. I am convinced that this is what caused the sound to tilt a bit to one side.

The test record and the balance control on my preamp helped me to solve the problem. And when I did, it was like… aaaaahh.

Your preamp’s balance control will set you free.
As God and the manufacturer intended.
Peace and long life.

Woof

While extremes of azimuth adjustment do have an apparent effect on channel balance, the cure is worse than the disease, because the stylus tip will be at a suboptimal angle to the groove resulting in aberrant wear on both the stylus and your LPs and audible distortion as well. I advise against adjusting azimuth to cure channel imbalance.

Some cartridges are just built like that.  I had a Dynavector XV-1S that had an imbalance - not much I could do except adjust azimuth by twisting the headshell. I hated doing that so I got rid of the cart. If it is the cart (your other carts do not have imbalance issues), you either need a great microscope or get a Fozgometer and test record to determine the extent of the imbalance. You can then decide if you want to live with it or get rid/retrip the cartridge.

@paulgardner This does not sound like a cartridge problem. You switched the leads and came up with nothing conclusive- this suggests the problem is something else.

The most likely problem is a tube. First identify the phono section tubes in your amp. Turn the amp off and swap the tubes that are the input to the phono section- this is where most of the gain is produced. Warm the amp up- did the problem move?

If yes you know the bad tube. If no, proceed to the next pair of tubes in the signal chain and perform the same procedure- continue this until the problem moves.

But- if you have a line level source like a CD player, try that. Does it have the channel imbalance? If no, the problem is only in the phono section. If yes, its not the phono at all. Perform the procedure above only starting with the preamp tubes at the line stage level. FWIW this could be power tubes as easily as any other tube so it will sound better when you get this sorted out.

Keep us informed- good luck.

paulgardner 

You've received a lot of good advice yet still have an imbalance problem .

Do you hear an imbalance with mono records ?

Do your classical symphony records have the correct orientation ?

Dealing with this problem for some time ? What did you change when it started ?

First have you switched everything left and right one by one !

from phono cables to speaker cables to left and right tubes .

Do you use a good magnifying glass when setting up your cartridge alignment ?

Do you have any old equipment , cables or tubes to switch in and out ?

Good Luck .

@mulveling its damn good looking cart! 

@paulgardner

You’re welcome! And yes, I agree the Zebrawood L is a solid choice. A really good embodiment and implementation of the "Benz" sound. Also I think it’s a very handsome cartridge!
All my Benzes so far have had excellent L/R channel balance. 

@mulveling wow thanks for the breakdowns. Super helpful! Sounds like the Zebrawood L is a good place to start. Like I said I really like the Hana SL but I think it’s time for a change and I hoping to smooth a bit of the top end harshness of the B&W 805s I sometime experience with some recordings. Much appreciated! 

@paulgardner

Hi Paul,

Here’s a rundown of my thoughts on the wood Benzes I’ve owned:

• Benz Wood 2M, SM (caramel colored Bruyere wood with swirly grain) - These are now discontinued. They have a lively, pleasing and fun sound with a little warmth in the mids. Not as refined, smooth, or detailed as the other Benzes on this list.
• Zebrawood L (new 2020 model to replace old "Wood" series) - Really nice cartridge for the price. Easy to work with in most system configurations. Great sonic balance, not too warm, not too bright. Definitely better than prior Wood series. This cart is probably the easiest Benz recommendation!
• Ebony L (replaces old "Reference" series) - A real chameleon. In some system configs this cart ends up a little leaner than I’d like in mids and bass, with top end a little too sharp. BUT is pairs brilliantly with gear that has gives very powerful bass response combined with a slightly relaxed (or at least flat) top end, like the Quadratic MC-1 SUT, the ARC Reference preamp & phono, or Apollo Dark monoblocks (in various combinations). When paired just right, the Ebony L exceeds the Zebrawood L. When the Ebony is really ON it competes even with my Koetsu Blue Lace. But the Zebrawood doesn’t require as careful system matching.
• LPS - This cartridge is hard to work with in two ways. One, its huge mass (16g) requires a lot of counterweight on your arm. I used a Graham Phantom with extra counterweight. Two, it doesn’t sound its best with a SUT, which is my preferred device for MC gain. You will want an active JFET MC stage that has high gain AND very low noise. I put this cart away a while ago and haven’t tried it with my ARC Ref 3SE yet, which should be its optimal partner. Before that, I got best results from the cheap little Hagerman Trumpet MC stage, and it sounded very good this way - but was miffed I couldn’t get super results with my VAC phono stage .

@mulveling 

yeah the channel imbalance is a challenge for sure! I did swap the L/R cartridge leads for a bit but went back because I couldn’t live with the flipped image. It did help though.

I really appreciate your replies here. Super insightful and very helpful. I was going to start a new discussion thread but maybe I’ll just ask you here - you once mentioned I could look at a Benz Micro wood cart as an upgrade to the Hana SL (which I really like) I’m running now. Which Benz wood should I consider? I feel like there  are a handful of Benz Wood carts out there. 
 

Thanks! 

L/R channel balance is definitely something that can drive me crazy. I’ve obsessed over it before. There are many sources of L/R imbalance in a 2ch audio system:

• acoustics / room
• cartridge - even high end MC cartridges are often spec’d at most to <= 0.5dB, sometimes as high as 1.0 or 1.5 dB!
• cartridge & arm setup
• mismatched tubes (usually this has to be a fairly large mismatch to notice, > 15% at least)
• speakers (really any transducer)
• speaker & listener positioning
• bad cable or contact connections (in particular, bad headshell contacts or leads have caused this for me in the past)

A test LP with a "center image" track (like the HiFiNews one) can be useful to help isolate imbalances. A "mono" switch on your pre/phono or a mono adapter cable (patch in as needed) can also be useful for diagnosis.

I have 2 high end preamps I alternate use of here: one without balance control (VAC Master), one with (ARC Reference 6). The Ref 6’s balance is implemented in such a way that engaging it does NOT degrade sonic performance. However some would argue the digital IC chip it uses for volume control compromises baseline performance, balance correction engaged or not. I enjoy both preamps. The Ref 6’s balance control is really nice but I try to not depend on it (because it’s not there with the VAC).

Clean all you cable connections, and sometimes I will swap channels L/R on certain slots (which takes experimentation), or tubes, in an effort to cancel out imbalances. For example, if you have a room asymmetry that makes R seem dominant, and you have a cartridge that is also R dominant (even after careful setup), swap the phono cabling so the cartridge’s R side reinforces the L instead of exacerbating the R imbalance. You would have to be willing to swap L/R image for this (which strangely doesn’t bug me). Some kinds of offset swaps you can do without mirroring channels.

My older preamp, Rogue Hera, has a high quality stepped attenuator for the main volume control (very transparent) and a cheap Alps Blue potentiometer (I can always hear the effect of these next to a higher quality control) for the balance control. When you engaged balance, the Alps got spliced into the circuit. That definitely affected SQ, and I couldn’t abide that. So any penalties of using the balance control will depend on implementation.

That is an excellent suggestion wlutke. No guesswork. Measure cartridge channel balance at phono leads. Measure cartridge channel balance at phono eq outputs. Measure preamp channel balance at preamp output. Measure channel balance at power amp outputs.

Measure at every stage for channel balance. The only other factors are room/speaker interface( measure with Sound Pressure Gauge at listening position?) or get ears checked for equal hearing response in each ear.

O-scopes are cheap these days, mine was about $225 on Amazon for a two channel. You can visually overlay the channels from a test record through the entire signal chain all the way to the speakers.  Easy to spot an imbalance.  

My post was general not specific to one individual member. I hope you solve your problem.

@theophile its not an inexpensive cartridge. 

Starting with the recorded vinyl record:

Not all have symmetrical balance.

Room placement, toe in, wall reflections can all influence balance.

At the turntable/ tonearm:

Antiskate, correct orientation of cartridge, Azimuth all will have a large influence. One cannot expect exact channel balance with inexact cartridge set up incorrect antiskate or azimuth.

The cartridge:

Ultra inexpensive cartridges cannot be expected to be as precisely accurate with regard to cartridge body to internal generator alignment. Costs are cut. So too are corners in quality..

Yep, don't count on recordings always having perfectly balanced center image. I especially hear this with 60's recordings when stereo first became ubiquitous, engineers really liked to play with panning, separation, often hear vocalists slightly off to left. Seems like this was common practice, vocalist slightly off to right very rare.

Mono recordings can also expose an off center balance.  Play lots of mono recordings, you should have equal fill on both sides of the center. Try for the nicer mono recordings, those with wider perspective, crap mono recordings very narrow center image.

Stereo recordings can throw one off here, engineers, producers can do some pretty strange things.

Balance control is a tricky thing. You have to consider if, for instance, the vocalist was standing slight to the right or left of the mic 

It is unwise to judge channel balance based on “perfect” centering of a vocalist.  You have no idea what the sound engineer was after when he set up the recording session or what sort of mixing was done.  Very often, the vocalist appears to be standing just to the left of center, near to the piano, in a jazz recording.  With the bass, drums, and etc to the right or behind the vocalist.

I experience the same issue on some of my recordings.  Some simply don’t have a solid and stable center image; very frustrating.  At this point I would take some of those recordings to your friends’ and see if the same thing happens on their systems.  Good luck.

@frogman good call on the subs. Mine are in opposite placement of each other. One in the front corner, the other is just to the left of my listening position. I tried turning them both off. Imbalance is still present. What if I told you that the imbalance is present on roughly 60-70% of my records. The imbalance causes the vocals to lean slightly left on 60-70% of my records. The other 40% of my records vocal are dead center and don’t require me to use the balance control. I realize this sounds slightly insane but it is what I’m hearing. I’ve had friends confirm they’re hearing the same thing so I know I’m not completely out of my mind. 

Good point. Our eyesight is not perfectly balanced either. In fact, each eye will also see very slightly different colors that are 'adjusted' by the brain. 

 Good point about the subs too. I only use one, and there is no doubt that it contributes to the left side because of its physical location. 

I feel your “pain”; I too am very sensitive to channel balance issues and one can really obsess over it. The first obvious question which you haven’t answered is have you always had this issue, or did you make an equipment change, including cabling, around the time that you started noticing the problem?.

**** I did swap the interconnect on the phono pre but couldn’t really tell if the imbalance moved or not. ****

This tells me that the issue is pretty subtle and probably with the room and not your gear; except perhaps with the subs. Otherwise, you should be able to clearly hear whether the imbalance jumped to the other side or not. Here’s what I would try and what worked for me (I too use a pair of subs, and I don’t have a balance control):

I assume you have your two subs situated L/R; one for each channel. First, turn off the subs and see (hear) if you still have the same issue. I would wager that the issue goes away. Bass frequencies and resulting room nodes are often the issue; it was in my case. Even if your room is symmetrical, if one side has a load bearing wall and the other does not, or has a closet and the other does not, each side will reinforce or absorb bass frequencies differently. The effect of this can impact our perception of the midrange. Then, swap the subs. It is possible that one is producing slightly more output than the other, or they are not exactly the same at the xover frequency settings. If nothing changes, then you know that the subs are not the problem and it is the room. I was able to, if not entirely fix the problem, greatly improve matters by slightly adjusting the output of one sub relative to the other.

Good luck.

Btw, don’t assume that because you have no ear wax that your hearing acuity is the same in both ears.

It’s probably the cart. The Puffin balances them out.

Compare temporarily to a CDP etc.

I dealt with it for many years before I got a Puffin. The important thing to remember is that any "degradation" from the balance pot is most likely already there if you use it or not. My pre has no balance pot, all electronic.

What’s so hard about trying and listening?

I just got a Herron 360. It's balance control is a welcome feature.

If you already have a balance control in circuit, I say use it. I have the same problem but it is my room and my hearing combined. One slight difference added to another slight difference can matter. In some cases, speaker toe in may help.

 Yah, it's enough to drive us in circles!

In some ways I wouldn't sweat a slight use of the balance control, but it also could be something is wrong; so you need to figure out if its the cart, phono or otherwise....

@fuzztone yeah my main concern is sound degradation.

@sns room is symmetrical and hearing is good. No wax. 

@solypsa 

I have not tried that one. I did swap the interconnect on the phono pre but couldn’t really tell if the imbalance moved or not. 
 

Here’s what I’m running:

Hana SL cart

Clearaudio Ovation table w/ Magnify tonearm

Herron Audio VTPH-2 phono stage 

Cronus Magnum II integrated Amp w/ signal tubes rolled to Gold Lions - Brimmer in the center position 

Bowers & Wilkins 805 d3 stand mount speakers

2 Rel S-510 subs

Kimber interconnects and speaker cables

Is room symmetrical? Sometimes channel imbalances may be due to room differences one side to the other, in this case asymmetrical placement of speakers needed.

Could also be hearing related, have ears checked, wax build up possible as well.

My carts vary from +1.1 to -0.6 on the left channel, quite noticeable.

Are you asking if we can hear any degradation from your balance control?

Unless it can be switched out any "degradation" is built in.

Did you switch leads at the cart to determine if the imbalance is with the cart?

A balance control is another potentiometer in the circuit. If done well you are probably ok. Care to be more specific about your system?